The results of the investigations to reference values for Na(+)- and Cl(-)-concentrations in sweat of adults are as follows: The normal range of electrolyte values in sweat in adults is up to 70 mmol/l (Na+) and 55 mmol/l (Cl-) respectively in infants (40 mmol/l for Na+ and Cl-). There are no sex and age differences. Adults with chronical bronchitis and bronchiectasis don't show different results in comparison with healthy persons. Adults with cystic fibrosis have significantly increased sweat electrolyte concentrations (90-120 mmol/l). Variations in the electrolyte values of a day or of a month are important and much higher than the analytical one.